国槐树

国 = 囗 + 玉 : Mnemonic symbol: a nation's flag. Let's say the Chinese flag.

In the observatory's kitchen (o2) Gitta Giraffe (gu) is practising her ballet performance. She got a whole crate (囗) full of jade bracelets (玉) and flags (国) and fixed one flag to each jade bracelet. This makes a perfect combination for throwing the ring with the flag waving behind it and catching the ring again after a few pirouettes.

树 = 对 + 木 : Sheldon Shrimp cultivates a Christmas tree in the space station's bathroom. He is very happy that he found the right tree, just the one he imagined, and—in his mind—marks of the tree he imagined with a big green check mark.